From: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
CFQ may preempt the queue currently in service if a new request, for a
different queue, happens to be close to the last-dispatched
request. This boosts the throughput with processes that issue close
requests, but whose I/O patterns are not regularly interleaved enough
to trigger the activation of the queue-merging heuristic removed in
the previous commit. BFQ does not need to perform any such preemption,
because the queue-merging mechanism of BFQ (EQM) is reactive enough to
merge queues also in the presence of irregularly interleaved I/O.
Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
---
block/cfq-iosched.c | 13 -------------
1 file changed, 13 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 10761b5..1ab8898 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2696,12 +2696,6 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
return cfqd->last_position - blk_rq_pos(rq);
}
-static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
- struct request *rq)
-{
- return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
-}
-
/*
* Determine whether we should enforce idle window for this queue.
*/
@@ -3751,13 +3745,6 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
return false;
- /*
- * if this request is as-good as one we would expect from the
- * current cfqq, let it preempt
- */
- if (cfq_rq_close(cfqd, cfqq, rq))
- return true;
-
return false;
}
--
1.9.1
--
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